In recent years, the earth's environment has greatly affected by manufacture, a consuming society, and business activity. The influence is incomputable. For example, air pollution, water pollution, and soil pollution due to wastes cause the deterioration of an ecosystem by a food chain and global warming. Therefore, CSR, environment, business, and laws and regulations that are inseparable from the business activity have become important. For this reason, it becomes to be important to develop a technique capable of contributing to the improvement and conservation of the environment. For example, the importance of the analysis of metal ions, such as copper ions, cadmium ions, lead ions, chrome ions, and mercury ions, which are important in a manufacturing field and an environmental field has increased. From this point of view, a “surface potential measurement-type sensor device” has been proposed as an analysis technique (for example, see Patent Document 1). This technique uses the analysis function of a self-assembled film. The analysis principle is as follows: when ion atoms are attracted to a self-assembled film provided at the leading end of an electrode, a work function varies from a position corresponding to the Fermi level of a base before and after the ion atoms are attracted, and the variation in potential is measured based on a reference electrode to analyze the concentration of a very small amount of solution. It is considered that this technique has the following effects:
1) The potential variation reaches a specific potential corresponding to the attracted ions (it is possible to selectively perform analysis corresponding to a molecular film structure);
2) The specific potential does not depend on the area of the electrode (since a current is not measured, a measurement system is simple and there is a strong possibility that the size of the system will be reduced);
3) The time required for the potential to reach the specific potential is proportional to the area of the electrode (it is possible to perform analysis in a wide range); and
4) It is possible to repeatedly perform analysis a maximum of twenty times by EDTA cleaning.
The inventors has pursued analysis using an electrochemical analysis method in which the self-assembled film is not provided on the electrode, according to an analysis target. However, the inventors found that this method had the following problems, similar to the self-assembled sensor.
When this technique is applied to a complex system sample (hereinafter, simply referred to as a “complex system”) in which a material included in an analyte is not known or the concentration of the material is not known even though the kind of material is known, a technique for more selectively analyzing the material is needed. Therefore, it is indispensable to increase the number of electrodes for analyzing a multi-component system, and a multi-layer wiring technique capable of reducing the size of a system even when the number of measuring electrodes is increased is more advantageous than a technique for forming a single-layer wiring substrate. That is, an effectively manufacturing technique capable of corresponding to the multi-layer wiring technique as well as the single-layer wiring substrate is required for the measuring substrate. In recent years, an inorganic substrate, such as a glass, ceramic, or mica substrate, has been used as an electrochemical measuring substrate, and a vacuum process, such as sputtering or vapor deposition, has been performed to form wiring lines. This process is effective in miniaturizing the wiring line, but it is difficult to reduce manufacturing costs and form a multi-layer structure.
An example in which an organic substrate used in the printed circuit board industry is used as the measuring substrate has not been known.
As the main multi-layer wiring technique generally known in the printed circuit board industry, there is a through hole connection technique which is a combination of drilling and a plating process, which has generally been known. However, in the technique, since holes are formed in all layers, there is a limit in the accommodation of wiring lines. In order to reduce the volume of holes provided in a connection portion, a build-up technique has generally been used which repeatedly performs the formation of an insulating resin composition layer, boring, and the formation of a circuit. The build-up technique is mainly divided into a laser method and a photolithography method. The laser method radiates a laser beam to form holes in the insulating resin composition layer. The photolithography method uses a photosensitive hardener (photoinitiator) for the insulating resin composition layer, puts a photomask on the insulating resin composition layer, and performs exposure and development to form holes. In addition, in order to further reduce manufacturing costs and increase density, some interlayer connection methods have been proposed. Among them, a method capable of omitting boring and a conductive layer plating process has drawn attention. In the method, first, a conductive paste is printed on wiring lines on a substrate to form a bump, an interlayer connection insulating material and a metal layer in a B stage are arranged, and the bump is inserted into a molding resin by a press to be electrically connected to a metal layer. The method of inserting the bump has been published in the scientific society or the newspaper, and has widely been known in the printed circuit board industry (for example, see Non-Patent Documents 1 and 2).
There is a collectively laminating method as a more efficient forming method. A wiring plate has been proposed which is integrally formed by printing holes, a connection conductor, and wiring lines on a ceramic body, which is called a green sheet before sintering, aligning them, and applying heat and pressure. However, since the plate is shrunken by about 20%, numerical stability is low. In addition, since the plate is made of an inorganic material, it is expensive. As a collectively laminating method that uses an organic material and does not require a boring process, there is a collectively laminated substrate conceived by the inventors including Nakamura (for example, see Patent Document 2). This method uses an insulating substrate made of a thermoplastic liquid crystal polymer.
In the method of forming a multi-layer structure, for example, plating, etching, printed wiring, and a wiring transfer method have been used to form a fine wiring line.
In the analysis of a complex system, it is very difficult to directly contact a sensor with a liquid to be extracted and analyzed and selectively analyze target metal ions. Even when a component system has been known, other metal ions preventing analysis or an analysis preventing material is included in the target metal ions when the concentration of the metal ions is selectively analyzed, which significantly reduces the possibility of analysis. The analysis of a monovalent copper chemical species is given as an example. In this case, the monovalent copper chemical species is a simple monovalent copper ion, a monovalent copper ion complex, or a composite chemical species including monovalent copper.
For example, the analysis of the monovalent copper chemical species is used to identify protein and sugar.
In addition, in an electrochemical measuring method in a filled via copper plating solution that covers a structure portion having a hole with the bottom with copper and forms a flat wiring layer, the measurement of the potential of a constant current at a cathode is used to evaluate a filled via property. However, it is difficult to qualitatively and/or quantitatively analyze a monovalent copper chemical species even though there is a plurality of metal ions or an analysis preventing material and the principle of a measurement method thereof is considered.
For the filled via copper plating solution, the monovalent copper ion deteriorates the filled via property a little, and it is preferable to qualitatively and quantitatively analyze the filled via copper plating solution. However, it is not certain that the plating preventing chemical species deteriorating the filled via property is the monovalent copper ion, the monovalent copper ion complex, the composite chemical species including monovalent copper, or a produced compound included in the plating solution that is used. When there is a large amount of divalent copper or an analysis preventing material, it is difficult to qualitatively and quantitatively analyze a target plating preventing chemical species and a produced compound selectively.
In the invention, the electrochemical analysis method means a method which immerses a plurality of electrodes in a liquid to be analyzed, applies a voltage or a current between the electrodes, and observes a variation in the current or the voltage. In the method, a plurality of strip-shaped gold thin films that are adhered on a glass substrate and extend in one direction substantially in parallel to each other are used as the electrodes.
Since the electrode is connected to a measuring device, a portion of the electrode needs to protrude from the liquid to be analyzed to the outside. The contact area of the electrode with the liquid to be analyzed is changed by, for example, the depth of immersion and the inclination of the substrate during immersion. In this case, the reproducibility of the analysis result is not ensured. In particular, there is a problem in the reproducibility of quantitative analysis. Therefore, it is important to insulate a wiring line from, for example, a liquid, mist, or gas, which is an analysis target, separate the electrode from the wiring line, and ensure a predetermined area of the electrode. It is important to provide an insulating portion on the wiring line, but it is difficult to effectively form the layer on a glass substrate at a low cost.
It is difficult to repeatedly use the electrode for a long time since it is contaminated, modified, and plated in the analysis process, and the electrode is regarded as an article of consumption. Therefore, in order to frequently use an inorganic substrate, such as a glass substrate, having electrodes formed thereon for field water quality analysis for managing chemicals and a work environment in the manufacturing line, it is preferable that the substrate be manufactured at a low cost.
The inventors have conducted an examination on the application of an organic substrate to electrochemical measurement and surface potential. As a result of the examination, the organic substrate has two main problems. The first problem is chemical resistance. When a liquid to be extracted and analyzed is a strong acid or a strong alkali, ions or molecules that prevent or increase an analysis function are likely to be generated from the organic substrate during analysis. In addition, the decomposition of an organic material forming the organic substrate, the remaining solvent, various kinds of additives, an ion material attracted during a wiring process, and a material absorbed from the air cause the generation of the analysis preventing ions or molecules.
The second problem is heat resistance. This is because it is necessary to form a carbon layer, which is an inert layer, such as a gold or platinum layer, on the electrode in the electrochemical analysis. (It is preferable that the carbon layer be formed of 100% of carbon. However, when an additive, such as a binder or a dispersant, is used in the component, impurities are removed such that the purity of the additive is approximately 100%. Hereinafter, a layer that includes carbon as a component and serves as an inert layer is referred to as a carbon including layer, and a material is referred to as a carbon including material. In addition, coating with the carbon including layer is referred to as carbon coating. The shape of carbon may be a particle or a carbon filament). For example, in general, a DLC method has been used to form the carbon including layer in which the content of carbon is approximately 100%, in terms of characteristics thereof, and a base material is exposed to a high temperature of 200° C. or more. In high-accuracy analysis, in a vapor deposition process and/or a sputtering process, the precipitation of impurities that are decomposed and generated prevents analysis. Therefore, an organic resin having high chemical resistance and high heat resistance, such as polyimide or liquid crystal polymer, in the method of forming a multi-layer wiring substrate is considered as an insulating material for a substrate for a sensor. However, this material is not necessarily selected, but there is a difficulty in a reduction in cost and the degree of recognition or spread in the industry. In particular, it is considered that the decomposition of an organic material at the adhesion interface or the bonding interface between an insulating material and a buried electrode causes the most serious problem. In this case, a liquid to be extracted and analyzed is infiltrated into the interface, which results in a variation in the area of the electrode during measurement or when the electrode is repeatedly used.
In the analysis of a complex system, that is, in high-accuracy analyze, a pre-process is needed. In many case, a complicated pre-process is needed. For example, an organic ligand, a filtering method, and a calorimetric method using absorbance measurement are performed to analyze monovalent copper (for example, see Non-Patent Document 3). This analysis method is relatively simple and has high selectivity. However, in order to put this analysis method to practical use, it is necessary to reduce the time required for a pre-process or analysis.    Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2006-058020    Patent Document 2: WO/2003/056889    Non-Patent Document 1: Hiroshi Ohira, other two persons: Proposal of Printed Circuit Board by New Manufacturing Process (B2it), 9th Proceedings of JIEP (Japan Institute of Electronics Packaging) Annual Meeting, ISSN0916-0043, 15A-10, PP. 55-56, (March, 1995)    Non-Patent Document 2: Takahiro Mori, other five persons: Application and Miniaturization of Substrate by Interlayer Connection Technique Using Bump, 10th Proceedings of JIEP Annual Meeting, ISSN0916-0043, 15A-09, PP. 79-80, (March, 1996)    Non-Patent Document 3: “Introduction of Research Results in Technology Techno Report (2002)”, Osaka Municipal Technical Research Institute, Published July, 2003, p. 14 (URL:http://www.omtri.city.osaka.jp/)